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authorCatalin Marinas <catalin.marinas@arm.com>2022-06-10 18:21:39 +0300
committerWill Deacon <will@kernel.org>2022-07-07 12:48:37 +0300
commit70c248aca9e7efa85a6664d5ab56c17c326c958f (patch)
tree1cee0c376af4662b3f7bf8982187e3492dff1b63 /mm
parented0a6d1d973e9763989b44913ae1bd2a5d5d5777 (diff)
downloadlinux-70c248aca9e7efa85a6664d5ab56c17c326c958f.tar.xz
mm: kasan: Skip unpoisoning of user pages
Commit c275c5c6d50a ("kasan: disable freed user page poisoning with HW tags") added __GFP_SKIP_KASAN_POISON to GFP_HIGHUSER_MOVABLE. A similar argument can be made about unpoisoning, so also add __GFP_SKIP_KASAN_UNPOISON to user pages. To ensure the user page is still accessible via page_address() without a kasan fault, reset the page->flags tag. With the above changes, there is no need for the arm64 tag_clear_highpage() to reset the page->flags tag. Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Andrey Konovalov <andreyknvl@gmail.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Link: https://lore.kernel.org/r/20220610152141.2148929-3-catalin.marinas@arm.com Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page_alloc.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index e008a3df0485..f6ed240870bc 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2397,6 +2397,7 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
bool init = !want_init_on_free() && want_init_on_alloc(gfp_flags) &&
!should_skip_init(gfp_flags);
bool init_tags = init && (gfp_flags & __GFP_ZEROTAGS);
+ int i;
set_page_private(page, 0);
set_page_refcounted(page);
@@ -2422,8 +2423,6 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
* should be initialized as well).
*/
if (init_tags) {
- int i;
-
/* Initialize both memory and tags. */
for (i = 0; i != 1 << order; ++i)
tag_clear_highpage(page + i);
@@ -2438,6 +2437,10 @@ inline void post_alloc_hook(struct page *page, unsigned int order,
/* Note that memory is already initialized by KASAN. */
if (kasan_has_integrated_init())
init = false;
+ } else {
+ /* Ensure page_address() dereferencing does not fault. */
+ for (i = 0; i != 1 << order; ++i)
+ page_kasan_tag_reset(page + i);
}
/* If memory is still not initialized, do it now. */
if (init)